---
title: Markdown
description: How to write documents
---

## Introduction

Fumadocs provides many useful extensions to MDX, a markup language. Here is a brief introduction to the default MDX syntax of Fumadocs.

> MDX is not the only supported format of Fumadocs. In fact, you can use any renderers such as `next-mdx-remote` or CMS.

## MDX

We recommend MDX, a superset of Markdown with JSX syntax.
It allows you to import components, and use them right in the document, or even export values.

See:

- [MDX Syntax](https://mdxjs.com/docs/what-is-mdx/#mdx-syntax).
- GFM (GitHub Flavored Markdown) is also supported, see [GFM Specification](https://github.github.com/gfm).

```mdx
---
title: This is a document
---

import { Component } from './component';

<Component name="Hello" />

# Heading

## Heading

### Heading

#### Heading

Hello World, **Bold**, _Italic_, ~~Hidden~~

1. First
2. Second
3. Third

- Item 1
- Item 2

> Quote here

![alt](/image.png)

| Table | Description |
| ----- | ----------- |
| Hello | World       |
```

### Images

Images are automatically optimized for `next/image`.

```mdx
![Image](/image.png)
```

### Auto Links

Internal links use the `next/link` component to allow prefetching and avoid hard-reload.

External links will get the default `rel="noreferrer noopener" target="_blank"` attributes for security.

```mdx
[My Link](https://github.github.com/gfm)

This also works: https://github.github.com/gfm.
```

### Cards

Useful for adding links.

```mdx
import { HomeIcon } from 'lucide-react';

<Cards>
  <Card
    href="https://nextjs.org/docs/app/building-your-application/data-fetching/fetching-caching-and-revalidating"
    title="Fetching, Caching, and Revalidating"
  >
    Learn more about caching in Next.js
  </Card>
  <Card title="href is optional">Learn more about `fetch` in Next.js.</Card>
  <Card icon={<HomeIcon />} href="/" title="Home">
    You can include icons too.
  </Card>
</Cards>
```

<Cards>
  <Card
    href="https://nextjs.org/docs/app/building-your-application/data-fetching/fetching-caching-and-revalidating"
    title="Fetching, Caching, and Revalidating"
  >
    Learn more about caching in Next.js
  </Card>
  <Card title="href is optional">Learn more about `fetch` in Next.js.</Card>
  <Card icon={<HomeIcon />} href="/" title="Home">
    You can include icons too.
  </Card>
</Cards>

#### "Further Reading" Section

You can do something like:

```tsx title="page.tsx"
import { getPageTreePeers } from 'fumadocs-core/server';
import { source } from '@/lib/source';

<Cards>
  {getPageTreePeers(source.pageTree, '/docs/my-page').map((peer) => (
    <Card key={peer.url} title={peer.name} href={peer.url}>
      {peer.description}
    </Card>
  ))}
</Cards>;
```

This will show the other pages in the same folder as cards.

<DocsCategory url="/docs/ui/navigation" />

### Callouts

Useful for adding tips/warnings, it is included by default. You can specify the type of callout:

- `info` (default)
- `warn`
- `error`

```mdx
<Callout>Hello World</Callout>

<Callout title="Title">Hello World</Callout>

<Callout title="Title" type="error">
  Hello World
</Callout>
```

<Callout>Hello World</Callout>

<Callout title="Title">Hello World</Callout>

<Callout title="Title" type="error">
  Hello World
</Callout>

### Headings

An anchor is automatically applied to each heading, it sanitizes invalid characters like spaces. (e.g. `Hello World` to `hello-world`)

```md
# Hello `World`
```

#### TOC Settings

The table of contents (TOC) will be generated based on headings, you can also customise the effects of headings:

```md
# Heading [!toc]

This heading will be hidden from TOC.

# Another Heading [toc]

This heading will **only** be visible in TOC, you can use it to add additional TOC items.
Like headings rendered in a React component:

<MyComp />
```

#### Custom Anchor

You can add `[#slug]` to customise heading anchors.

```md
# heading [#my-heading-id]
```

You can also chain it with TOC settings like:

```md
# heading [toc] [#my-heading-id]
```

To link people to a specific heading, add the heading id to hash fragment: `/page#my-heading-id`.

### Codeblock

Syntax Highlighting is supported by default using [Rehype Code](/docs/headless/mdx/rehype-code).

````mdx
```js
console.log('Hello World');
```
````

You can add a title to the codeblock.

````mdx
```js title="My Title"
console.log('Hello World');
```
````

#### Shiki Transformers

We support some of the [Shiki Transformers](https://shiki.style/packages/transformers), allowing you to highlight/style specific lines.

````md tab="Input"
```tsx
// highlight a line
<div>Hello World</div>  // [\!code highlight]

// highlight a word
// [\!code word:Fumadocs]
<div>Fumadocs</div>

// diff styles
console.log('hewwo'); // [\!code --]
console.log('hello'); // [\!code ++]
```
````

```tsx tab="Output"
// highlight a line
<div>Hello World</div>  // [!code highlight]

// highlight a word
// [!code word:Fumadocs]
<div>Fumadocs</div>

// diff styles:
console.log('hewwo'); // [!code --]
console.log('hello'); // [!code ++]
```

#### Tab Groups

You can use code blocks with the `<Tab />` component.

````mdx
import { Tab, Tabs } from 'fumadocs-ui/components/tabs';

```ts tab="Tab 1"
console.log('A');
```

```ts tab="Tab 2"
console.log('B');
```
````

> Note that you can add MDX components instead of importing them in MDX files.

```ts tab="Tab 1"
console.log('A');
```

```ts tab="Tab 2"
console.log('B');
```

### Include

> This is only available on **Fumadocs MDX**.

Reference another file (can also be a Markdown/MDX document).
Specify the target file path in `<include>` tag (relative to the MDX file itself).

```mdx title="page.mdx"
<include>./another.mdx</include>
```

See [other usages](/docs/mdx/include).

## Additional Features

You may be interested:

<DocsCategory />

### Package Install

Generate commands for installing packages via package managers.

````md tab="Input"
```package-install
npm i next -D
```
````

```package-install tab="Output"
npm i next -D
```

To enable, see [Remark Install](/docs/headless/mdx/install).
